Atmospheric Corrosion of Carbon and Low Alloy Cast Steels

Nine carbon and low alloy cast steels cast in panel form, some machined and others unmachined, were exposed in marine and industrial atmospheres for periods of one-, three-, seven-, and 12-years and recorded as to weight loss information. The weight loss was converted to corrosion rate in terms of inches penetration per year (ipy) and milligrams lost per square decimeter per day (mdd). Comparisons were made and cast steels containing nickel, copper, or chromium as alloying elements have corrosion resistance superior to carbon cast steels or those containing manganese when exposed to atmospheric environments. Increasing the nickel and the copper contents of cast steel increases the corrosion resistance in all three atmospheric environments. Unmachined cast steel surfaces, with the casting “skin” intact, had no significant effect on the corrosion resistance of cast steels when compared to machined surfaces regardless of the atmospheric environment.